1. Field of the Invention
The present application relates to a process for preparing chloroamines of the formula (I) which can be used as precursors for syntheses of fine chemicals and active ingredients from pharmaceuticals and/or agriculture (Kovacic et al. Chemical Reviews 1970, 70, 6, 639).

It is known that, in secondary amines (II) where R1 and R2 are each independently selected from alkyl radicals or, together with the nitrogen atom to which they are bonded, may form a 5- or 6-membered ring, hydrogen can be exchanged for chlorine with a chlorinating agent.
2. Description of Related Art
In the case of sterically hindered secondary amines, very active N-chloroamides, for example N-chlorosuccinimide (Kovacic et al., Chemical Reviews 1970, 70, 6, 639) or sodium dichloroisocyanurate (Zakrzewski, Synthetic Communications 1988, 18 (16&17), 2135), are required as chlorinating agents. However, the yields are usually only moderate (75-86%) and, even when the yields are better (e.g.: J. Org. Chem. 1997, 62, 16, 5631), one equivalent of the amide is unavoidably obtained as waste, which is both economically and ecologically disadvantageous. The direct chlorination of 2,2,6,6-tetramethylpiperidine with sodium hypochlorite solution (commonly known as bleach or liquid bleach) is known (Ingold et al., JACS, 1973, 6400). The yield is only 77% and the dilutions of 100 ml of liquid bleach per 7 g of amine used in the reaction described lead to low space-time yields in an industrial process. A better yield (96.5%) was described by Toshimasa et al., Bull. Chem. Soc. Jap., 1972, 45, 1802. Here, however, for 28 g of 2,2,6,6-tetramethylpiperidine, 220 ml of aqueous HCl and 250 ml of liquid bleach were actually consumed. Such a great salt load is also disadvantageous in industry, and forms as a result of an excess of chlorinating agent which has to be degraded on the industrial scale at the end of the reaction. The formation, reported in Bull. Chem. Soc. Jap., 1972, 45, 1802, of 1-chloro-2,2,5,5-tetramethyl-4-oxoimidazolidine with 94% yield is described only with an excess of chlorinating agent and in the case of dilutions of 1.4 g of amine in 40 ml of liquid bleach. Fellous et al., Tetrahedron Lett., 2000, 9787, in the case of such chlorinations describe only yields of 76-91% according to the substrate. The 10 equivalents (eq.) of the chlorinating agent used also show that the synthesis of N-chlorodialkylamines on the industrially relevant scale remains an unsolved problem.
Inevitably, in the case of use of liquid bleach (NaOCl), at least one equivalent of additional salt is obtained (Scheme 1), often with formation of more than 2 equivalents thereof. For example, Bull. Soc. Chem. Jap. describes the formation of 2.66 equivalents of salt in order to fully scavenge the chlorine. Since the pH rises at the end of the reaction (as a result of formation of NaOH), the oxidation potential of the liquid bleach falls in the course of the reaction. This explains the incomplete reaction even if greater excesses of liquid bleach are used.

Spanswick et. al., Can. J. Chem., 1970, 48, 548 state that chloroamines in the presence of strong acids are themselves good chlorinating agents. Consequently, the scavenging of HCl formed is essential.
It is thus an object of the present invention to provide a process for preparing sterically hindered chloroamines which overcomes the above-described disadvantages.
The object was achieved by a process for preparing chloroamines of the formula (I)
    wherein R1 and R2 are each independently selected from the group consisting of (C1-C8)alkyl optionally substituted by 1-2 R3 radicals;    or    R1 and R2 together form a —(CH2)4—, —(CH2)5— or —(CH2)2O(CH2)2— group, where each of these groups may optionally be substituted by 1-4 R4 radicals;    R3 are each independently selected from halogen, (C1-C3)alkoxy, (C1-C3)haloalkoxy, (C1-C3)alkylamino, (C2-C4)dialkylamino and (C2-C4)alkoxycarbonyl;    R4 is selected from halogen, (C1-C3)alkyl, (C1-C3)alkoxy, (C1-C3)haloalkoxy, (C1-C3)alkylamino, (C2-C4)dialkylamino and (C2-C4)alkoxycarbonyl,    by reaction of secondary amines of the formula (II)
in which the R1 and R2 radicals are each as defined above with chlorine gas in the presence of an aqueous alkali metal or alkaline earth metal oxide base.